Masters Theses

David Shannon

Date of Award

12-1975

Degree Type

Thesis

Degree Name

Master of Science

Major

Animal Science

Major Professor

Robert R. Shrode

Committee Members

James B. McLaren, John D. Smalling

Abstract

Body measurements, including heart girth, body length, shoulder width, hip width, hip height, and chest depth were recorded on both Angus and Polled Hereford calves. These measurements were studied in-dividually and in combination to assess their value in estimation of live weight. The Angus calves used in this study were raised at the University of Tennessee Plateau Experiment Station, Crossville, Tennessee, while the Polled Hereford calves were raised at the University of Tennessee Tobacco Experiment Station, Greeneville, Tennessee. The calves were born in the years 1968 through 1974. More than 5,000 sets of records were taken from more than 1,600 different calves. A total of 63 simple and multiple regression equations were constructed. In addition, a number of stepwise regression analyses were conducted. When all of the variables were available to the program for possible inclusion as independent variables to estimate weight, the final equation would include all of the variables except hip height; and the coefficient of determination would be about 0.96. When all of the variables except heart girth were available for inclusion, the final equation would include all of them; and the coefficient of determination would be about 0.95. Chest depth was most highly correlated with weight (0.95), and heart girth was second (0.93). Hip height was found to be the variable least correlated with weight (0.86). The mean weight of calves studied was 211 kg with the range being 39 to 433 kg. It was concluded that in Angus and Polled Hereford calves weighing from 39 to 433 kg, an accurate estimation of weight could be made by using either chest depth or heart girth alone, but the coefficient of determination could be increased by adding additional measurements. However, the small increase in predictive value would not be justified in practice.

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